1. Field of the Invention
This invention relates to an image formation method and apparatus whereby an overlay image is obtained by combining different original images, and more particularly to an image formation method and apparatus in which different original images are converted into time-sequential electrical signals and such signals are combined and a combined image is obtained on the basis of the combined signal.
2. Description of the Prior Art
As a typical method of obtaining an overlay image, there is a method which comprises cutting out a portion of a sheet of original paper to form a window and copying with another original peeping out from this window. This method, however, is inconvenient in cumbersomeness of the procedure involved and damage imparted to the original. As another example, there is a method which comprises projecting an original by an optical system, and causing a character pattern electrically generated by a character generator to be depicted so as to be superposed on the projected original by the scanning of a laser beam or the like. This method does not require the procedure of cutting out a portion of the original paper and accordingly does not involve the danger of damaging the original, whereas it has suffered from a problem that it is very difficult to intercept the optical image of the desired portion of the original. Moreover, the limitation resulting from the utilization of the character pattern generated by the character generator is great.